• Korean Journal of Optics and Photonics
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• v.26 no.1
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• pp.30-37
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• 2015

The design and implementation of a radiative temperature measurement system for a flash light are carried out. Since a massive amount of energy is emitted within a very short time, it is impossible to measure the temperature of a flash with a conventional method. It is also irrelevant to measure one with an optical noncontact method. In this paper, a radiative temperature measurement system using the ratio of spectral radiances over mid- and long-wavelength infrared (IR) is designed and implemented. The implemented system utilizes optical bandpass filters to divide the wavelengths within the mid- and long-wavelength IR ranges, and pyroelectric IR detectors to measure the incident optical power of each wavelength-divided channel. It is shown that the measured radiative temperature of a flash is in the range of 1393 to 1455 K. This temperature-measurement system can be utilized to obtain information about the spectral radiance of a flash as a light source, which is of crucial importance to approaching the modeling and simulation of the various effects of a flash.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.671-686
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• 2004

The shock-induced combustion ramjet (shcramjet) is a hypersonic airbreathing propulsion concept which over-comes the drawbacks of the long, massive combustors present in the scramjet by using a standing oblique detonation wave (a coupled shock-combustion front) as a means of nearly instantaneous heat addition. A novel shcramjet combustor design that makes use of wedge-shaped flameholders to avoid detonation wave-wall interactions is proposed and analyzed with computational fluid dynamics (CFD) simulations in this study. The laminar, two-dimensional Navier-Stokes equations coupled with a non-equilibrium hydrogen-air combustion model based on chemical kinetics are used to represent the physical system. The equations are solved with the WARP (window-allocatable resolver for propulsion) CFD code (see: Parent, B. and Sislian, J. P., “The Use of Domain Decomposition in Accelerating the Convergence of Quasihyperbolic Systems”, J. of Comp. Physics, Vol. 179, No. 1,2002, pages 140-169). The solver was validated with experimental results found in the literature. A series of steady-state numerical simulations was conducted using WARP and it was deter-mined by means of thrust potential calculations that this combustor design is a viable one for shcramjet propulsion: assuming a shcramjet flight Mach number of twelve at an altitude of 36,000 m, the geometrical dimensions used for the combustor give rise to an operational range for combustor inlet Mach numbers between six and eight. Different shcramjet flight Mach numbers would require different combustor dimensions and hence a variable geometry system in or-der to be viable.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.6
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• pp.487-497
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• 2019

It is very difficult to detect ballistic missiles because of small cross-sections of the radar and the high maneuverability of the missiles. In addition, it is very difficult to recognize and intercept warheads because of the existence of debris and decoy with similar motion parameters in each flight phase. Therefore, feature vectors based on the maneuver, the micro-motion according to flight phase are needed, and the two types of features must be fused for the efficient recognition of ballistic warhead regardless of the flight phase. In this paper, we introduce feature vectors appropriate for each flight phase and an effective method to fuse them at the feature vector-level and classifier-level. According to the classification simulations using the radar signals predicted by the CAD models, the closer the warhead was to the final destination, the more improved was the classification performance. This was achieved by the classifier-level fusion, regardless of the flight phase in a noisy environment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.8
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• pp.759-765
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• 2013

This study proposes the characteristics of the pressure drop in a compressible fluid through porous media for application to a porous injector in a liquid rocket engine in order to improve the uniformity of the drop size distribution and the mixing performance of shear coaxial injectors. The fluid through the porous media is a Non-Darcy flow that shows a Nonlinear relation between the pressure drop and the velocity at high speed and high mass flow rate. The pressure drop of the Non-Darcy flow can be derived using the Forchheimer equation that includes the losses of viscous and inertia resistance. The permeability and Ergun coefficient represented as a function of the pressure drop and pore size can be applied to the porous injector, where the fluid through the porous media is compressible. A generalized correlation between the pressure drop in relation to the pore size was derived.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4828-4834
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• 2015

From the moment that a firing pin triggers the detonator to the moment that a grenade leaves a barrel is called Action Time. Since a loading and percussion of 40mm grenade happens simultaneously, action time should be within a certain time in order to prevent a Jamming malfunction. Previously, unreliable action time device of 40mm grenade made it difficult to improve quality assurance of K4 Grenade Machine Gun. Here, various sensors were compared and a special device was designed to seek an accurate measurement on action time. In this device, the gap between a signal from an optical sensor in Firing Pin and that from Eddy current probe in the barrel was recorded and data were sent to a computer in real time. Confirming if action time is within the criteria, it is expected that action time plays an important role in quality assurance on 40mm grenade.

• Journal of the Korean Magnetics Society
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• v.25 no.3
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• pp.83-86
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• 2015

Nowadays the weapon systems are employed air bursting munition (ABM) as smart programmable 40 mm shells which have been developed in order to hit the target with programmed munition that can be air burst after a set distance in the battlefield. In order to improve the accuracy of such a bursting time, by measuring the speed of the munition from the barrel, weapon systems calculate the exact time of flight to the target and then the time information must be inputted to the munition. In this study, we introduce a device capable of detecting a shot at K4 40 mm automatic grenade. The shot is composed of a rotating copper band to convert linear motion into rotary motion when it passes through the barrel, the steel section is exert the effect of fragment and aluminum section to give fuze information. The aluminum section was used to detect munition using eddy current method. To measure muzzle velocity by means of non-contact method, two eddy current probes separated 10 cm was employed. Time interval between two eddy current probe detection times was used as muzzle velocity. The eddy current probe was fabricated U-shape Mn-Zn ferrite core with enamelled copper wire, and 200 kHz alternating current was used to detect inductance change. Measured muzzle velocity using the developed sensor was compared to the Doppler radar system. The difference was smaller than 1%.

• Korean Journal of Agricultural Science
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• v.25 no.1
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• pp.79-88
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• 1998

This study was performed in order to apply to effective breeding of Korean native cattle on the molecular genetic level obtained from PCR and nucleotide sequencing analysis of BoLA DRB3 exon2 that has important roles in host immune defence. Genomic DNA used in this study was prepared from the blood of Korean native cattle in Korean Native Cattle Improvement Center of National Livestock Cooperation. The results obtained from this study are summarized as follows: 1. Genomic DNA extracted from the blood of Korean native cattle was subjected to electrophoresis on 1.5% agarose gel. Major band was bigger than 12.2kb, indicating that genomic DNA was well prepared for PCR. Amplified products of 284bp fragments was obtained the amplification of BoLA DRB3 exon2 gene by PCR. 2. Cloning of BoLA DRB3 exon2 of Korean native cattle with pCR2.1 vector was conformed by 300bp fragment from recombinent plasmid that restricted with enzyme digestion of EcoRI. 3. Homology of BoLA DRB3 exon2 alleles of parent was 82.0% between sire's alleles and 90.1% between dam's alleles. 4. In pedigree analysis using BoLA DRB3 exon2 gene, sequencing result of BoLA DRB3 exon2 genes showed inheritance by Mendelian mode through the parents to their offspring. 5. Taking together those experimental results, pedigree was confirmed on the basis of sequencing for the alleles of parents and offspring. This knowledge by the molecular biological approach could be served for the improvement of Korean native cattle.